Concerning Ziegler-Natta type catalysts which are effective in polymerizing olefins, catalyst components having transition metals deposited on a variety of carriers have been developed for the purpose of improving catalyst activity per unit amount of catalyst or decreasing residues originating in catalyst and persisting in produced polymer.
A plurality of catalyst components using silica, alumina, and other similar metal oxides as carriers for deposition of transition metals have been proposed. Most of them are intended for polymerization of ethylene. A very few of them are intended for polymerization of alpha-olefins such as propylene.
As concerns catalyst compositions for the polymerization of propylene, a catalyst component comprising a reaction product of a metal oxide and a magnesium dialkoxide brought in contact with an electron-donating compound and a tetravalent titanium halide (specification of Japanese patent application Laid-open No. SHO 58[1973]-162,607) and a catalyst component comprising a reaction product of an inorganic oxide and a magnesium hydrocarbyl halide compound brought in contact with a Lewis base compound and titanium tetrachloride (specification of Japanese patent application Laid-open No. SHO 55[1980]-94,909) are known to the art. These catalyst components, however, can hardly be called satisfactory in terms of activity and stereoregularity.
Further, a catalyst component obtained by causing a hydrocarbyloxysilane to react with a reaction product of a porous carrier such as silica and an alkyl magnesium compound and subsequently causing a titanium halide compound to react upon the resultant reaction product (specification of Japanese patent application Laid-open No. SHO 57[1982]-153,006) and a catalyst component obtained by causing an organic metal compound to react with a porous carrier, causing a hydrocarbyl alcohol to react with the resultant reaction product, and then causing a titanium halide compound to react with the reaction product (specification of Japanese patent application Laid-open No. SHO 57[1982]-200,408) have been proposed. These catalyst components are intended for homopolymerization of ethylene or for copolymerization of ethylene with other olefins. They are not suitable for polymerization of alpha-olefins such as propylene.